Land Mobile communication systems are known. Such systems typically consist of a plurality of mobile communication units, a plurality of repeaters, a communication resource allocator, and a plurality of communication consoles. Each communication console is constructed to participate in at least some communication transactions between communication units. The communication resource allocator provides the communication resources to facilitate such participation.
A important factor in the utility of console operation is an ability on the part of the communication resource allocator to recognize selected communication transactions and to transceive those transactions to an at least one console assigned to participate in those transactions. The transactions in which a particular console may participate are typically any transaction involving a communication unit within a particular communication group (talk-group). A communication group may comprise any communication unit involved in carrying out selected organizational, or otherwise related activity.
Operation of a conventional land mobile communication system (FIG. 1) and that of a trunked land mobile communication system (FIG. 2) are similar. Console operation and the console interface with the communication resource allocator within the two systems are substantially identical.
A communication resource allocator in a conventional system recognizes talk-groups based on the repeater from which the transaction originates. The repeater, in turn, is connected to a base interface module (BIM) within the communication resource allocator. The BIM may act as a signal receiver or a signal source. As a signal receiver the BIM receives the signal from the associated repeater, converts the signal into a digitized signal, and sources the signal into a slot on a TDM bus within the communication resource allocator.
The BIM may also act as a source of signal to the associated repeater by receiving signals from a slot on the TDM bus and transmitting the signal through the associated repeater to a communication unit serviced from the repeater. An example of a situation where a BIM can act as both a receiver and a source of signals is where two communication units are part of the same talk-group, but serviced from two separate repeaters or where a communication unit, serviced through a repeater, communicates with an console operator. In either case a signal from a first communication unit is received by a first repeater, inserted into a time slot on the TDM bus, and received by a second repeater for re-transmission to a second communication unit or received at a console by a console operator.
The slots on the TDM bus used by a repeater to source and receive signals are fixed during start-up of the repeater. Once inserted into a slot on the TDM bus, signals may be transceived with the TDM bus by a console through an interface with the communication resource allocator consisting of a operator interface mux module (OMI) and an audio expansion interface module (AEI). (For an operational description of the TDM bus and slot location, refer to Motorola Inc., Pub. No. R4-2-37C, CENTRACOM Series II Control Centers (March, 1988).)
Exchange of signals between a console and the TDM bus is performed by the AEI and OMI under the control of the OMI. The OMI contains, in personality firmware located within the OMI, information relative to certain supervisory functions controlled from the OMI for the console. (For a detailed description of and a list of supervisory functions, refer to Motorola, Inc. Pub. No. R4-2-73, CENTRACOM Series II Plus Control Centers (April, 1988).)
One of the supervisory functions performed by the OMI is the control of the AEI in receiving audio signals from slots on the TDM bus. By design the personality firmware within the OMI contains the IDs and time slots of specific talk-groups. The OMI provides timing control to the AEI for purposes of receiving the audio signals from specific slots and routing the signals to specific speakers.
Another supervisory function performed by the OMI is the transmission of audio signals from a console operator to a destination talk-group. The console operator first activates a "talk" button on a channel control module (CCM) within the console and then speaks into a microphone located on the console. The activation of the pushbutton alerts the OMI as to which talk-group the transmission is intended. The OMI, under control of the personality firmware, inserts the outgoing signal into an appropriate slot on the TDM bus.
Together the AEI and OMI under control of the OMI transceive signals between the TDM bus and the console. Audio signals from communication units (talk-groups) are routed as specified within the OMI by the AEI to the designated speaker for the talk-group within the console. Outgoing audio signals from the console are inserted into appropriate TDM slots on the TDM bus for transmission to communication units within a talk-group.
Contained within the console is a CCM for each talk-group. Identification of the talk-group associated with a specific CCM located within a console is defined in the personality firmware of the OMI. The CCM, in turn, interfaces directly with the OMI. The CCM through activation of a talk button located on the CCM thereby identifies through the OMI the destination talk-group for outgoing audio signals. The CCM also allows a console operator to control such talk-group parameters as audio volume and designated speaker, all under control of the OMI. The CCM, typically, allows a first designated speaker for non-priority monitoring and a second designated speaker for priority monitoring. Activation of a priority monitoring pushbutton on the CCM causes the AEI to route an audio signal to the second designated speaker for priority monitoring as designated within the OMI.
Typically, consoles contain more CCMs than speakers. Fewer speakers are needed because while only one talk-group may be assigned to a CCM, a number of audio signals from specific talk-groups, each controlled by a CCM, may be assigned to a speaker. The mixing of audio signals is controlled within the AEI, again, under the direct control of the OMI.
The number of talk-groups assigned to a console is typically limited by the number of CCMs contained within the console. As mentioned each CCM controls communication transactions between a specific talk-group and the console. Reassignment of a CCM, on the other hand, may be performed by a computer aided dispatcher (CAD) associated with the communication system or by a console operator. Reassignment of a CCM allows a console to participate in communication transactions with a different talk-group (at the expense of losing participation in original talk-group transactions).
Trunked mobile communication systems operate in a similar manner to the conventional system. One difference is that while in a conventional system the OMI is programmed to identify talk-groups by slot location, the OMI in a trunked system must be informed over a data bus of the slot location of a signal from a particular talk-group. The need for the greater sophistication in the operation of the trunked systems lies in the flexible use of repeaters.
In conventional systems talk-groups are associated with specific repeaters. In trunked systems, on the other hand, communications units request service from an available repeater. The repeater then transmits such requests for service to a communication resource central within the communication resource allocator. The communication resource allocator then identifies the talk-group within which the communication unit is a part and allocates a communication resource. The communication resource includes the TDM slot used by the repeater.
The communication resource central then transmits over a data bus the ID of the talk-group along with the ID of the signal slot used by the allocating repeater. OMIs participating in the talk-group, monitoring the TDM bus, and AEIs tune to the appropriate slots and transceive signals between the TDM bus and the console.
Talk-groups within conventional systems are defined within the OMI associated with a specific console. Changes in talk groups, consequently, may be made through a computer aided dispatcher (CAD) in contact with the OMI or through the console by a console operator. Talk-groups may be de-assigned at certain consoles and added to other consoles. Changes in the composition of talk-groups in conventional systems, on the other hand, must be made by the exchange of communication units since inclusion in a talk group is defined by the repeater servicing the talk-group.
Changes in talk-groups within trunked systems are somewhat more flexible. Inclusion within talk-groups in a trunked system is based upon the IDs of communication units within the communication resource central. Grouping of communication units into specific talk-groups is also contained within memory within the communication resource central. Changes of the composition of talk-groups, consequently, may be made from a terminal connected to the communication resource central. Assigning and deassigning talk-groups from consoles may be made in the same manner as with a conventional system.
Changes to the operation of the console, on the other hand, is somewhat more difficult. Operation of the console is controlled through the personality firmware contained within the OMI. The operator has only limited access to the personality firmware through a CRT located on a CRT Console (For an operational description of the CRT Console, refer to Motorola Inc., Pub. No. 68P81120E38-A, CENTRACOM Series II Control Centers (June 25, 1988).) or through pushbuttons and switches on a Buttons and LEDs Console (For an operational description of the Buttons and LEDs Console, refer to Motorola Inc., Pub. No. 68P81114E48-E, CENTRACOM Series II Control Centers (Nov. 30, 1988--UP).)
The instructions contained within the firmware define how the console operates. The personality firmware defines a speaker designation for priority monitoring and speaker designation for non-priority monitoring.
Changes to a console must be made by shutting down the system and loading different firmware into the OMI. Communication activity within a communication console, on the other hand, is of a dynamic nature. Levels of communications activity within a talk-group may vary hourly or even by the minute. Talk-groups assigned to one designated speaker may assume a different level of activity while another designated speaker may, simultaneously, experience a low level of activity. A need therefore exists for a way to dynamically modify speaker assignment in a more flexible manner from the console while the console is in normal operation.